1. Field of the Invention
The present invention relates to a substrate processing apparatus, and particularly to a semiconductor wafer processing apparatus.
2. Description of the Related Art
FIG. 1 is a perspective view for explaining a conventional semiconductor wafer processing apparatus, and FIG. 2 is a cross-sectional view for explaining the conventional semiconductor wafer processing apparatus.
This conventional semiconductor wafer processing apparatus is composed of a wafer transfer chamber 150, which has a hexagonal shape as viewed from above, cassette chambers 131 and 132, wafer cooling chambers 141 and 142, and reaction chambers 171 and 172. The cassette chambers 131 and 132, the wafer cooling chambers 141 and 142, and the reaction chambers 171 and 172 are disposed on the side walls of the wafer transfer chamber 150. The wafer transfer chamber 150 is provided with a wafer transfer robot 160, an arm 166 of which is located within the wafer transfer chamber 150. The cassette chamber 131 (132) has a cassette elevator 129, which hoists and lowers a cassette 110 disposed within the cassette chamber 131 (132). The cassette 110 is loaded with a plurality of wafers 105 arranged vertically in layers. A gate valve 193 is disposed between the reaction chamber 171 (172) and the wafer transfer chamber 150; a gate valve 192 is disposed between the wafer transfer chamber 150 and the cassette chamber 131 (132); and the cassette chamber 131 (132) is also provided with a front door valve 191 for carrying in/out a cassette.
This conventional semiconductor wafer processing apparatus performs the following series of operations: the cassette 110 loaded with a plurality of wafers 105 is carried into the cassette chamber 131 (132) through the front door valve 191; the cassette 110 is then lifted or lowered to a predetermined height by the cassette elevator 129 within the cassette chamber 131 (132); a wafer 105 is then transferred by the arm 166 of the wafer transfer robot 160, from the cassette 110 located within the cassette chamber 131 (132) to the reaction chamber 171 (172); the wafer 105 then undergoes a predetermined processing, such as film deposition, in a heated state within the reaction chamber 171 (172); the processed wafer 105 is then transferred by the arm 166 of the wafer transfer robot 160 to the wafer cooling chamber 141 (142), where the wafer 105 is cooled to a predetermined temperature; and the cooled wafer 105 is then transferred into the cassette 110 by the arm 166 of the wafer transfer robot 160.
As described above, in the conventional semiconductor wafer processing apparatus, since the cassette 110 cannot hold a high-temperature wafer 105, a processed wafer 105 is first transferred from the reaction chamber 171 (172) to the wafer cooling chamber 141 (142) so as to be cooled to a predetermined temperature, and then the cooled wafer 105 is transferred to the cassette 110. Accordingly, the wafer cooling chamber 141 (142) must be provided in addition to the cassette chamber 131 (132).
However, the presence of the wafer cooling chamber 141 (142) increases the area occupied by the semiconductor wafer processing apparatus within a clean room accordingly. Further, the number of sides of the wafer transfer chamber 150 increases accordingly, resulting in an increase in the area occupied by the wafer transfer chamber 150. This also increases the area occupied by the semiconductor wafer processing apparatus within the clean room, resulting in an increased running cost.